One vertex per element, one color per generator, with an edge from x to x·s.
(5,6)(7,11)(8,9)(10,12)(13,14,17,19)(15,21,22,28)(16,25,23,20)(18,26,27,24)(1,2)(3,4)(5,6)(7,10)(8,9)(11,12)(13,15,16,24,17,22,23,26)(14,18,20,21,19,27,25,28)(6,9)(10,11)(14,19)(15,22)(20,25)(24,26) involution — undirected(2,4)(5,7,8,12)(6,10,9,11)(14,19)(18,27)(20,25)(21,28)(13,15,23,26,17,22,16,24)(14,18,25,28,19,27,20,21)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.